\begin{table}%t4
\caption{\label{tab:tricouplers_wb}Tricoupler   splitting   ratio measured in wide band.  The dispersion (rms) over 1024~measurements is~0.1\%. The  two first lines  correspond to the wide  band experiments while the third gives the  average value and the variation amplitude over the wavelength range.} 
%\centering
\small
\begin{tabular}{c|cccc}
\hline
\hline
 $T$ & $T_{1}$ & $T_{2}$ & $T_{3}$ & $T_{4}$\\
 \hline
 Chip 1 & 33.7--33.3--32.8 &
 33.2--32.6--34.1 & 34.5--35.0--30.3 & 34.2--35.9--29.8 \\
\par
 Chip 2 & 31.9--35.3--32.7 &
 33.8--34.0--32.1 & 32.4--36.4--31.1 & 34.3--34.0--31.6 \\
\par
avg /$\Delta \lambda$ & 32.2/10.5--37.2/2.9--30.5/11.9 & 
 32.9/18.6--31.4/6.2--35.6/13.2 & 32.1/2.6--37.0/17.9--30.8/19.0 &
 31.3/9.9--37.1/5.0--31.4/14.2\\
\hline
\end{tabular}
\end{table}